US20070137897A1

US20070137897A1 - Combined directional and impact drilling motor

Info

Publication number: US20070137897A1
Application number: US11/305,607
Authority: US
Inventors: Michael Sanders; Jerry Foster; Duane Bennett
Original assignee: KENTUCKY AIR DRILLING SYSTEMS Inc
Current assignee: KENTUCKY AIR DRILLING SYSTEMS Inc
Priority date: 2005-12-16
Filing date: 2005-12-16
Publication date: 2007-06-21

Abstract

A directional drilling mechanism is disclosed. The mechanism is also an impact drill.

Description

FIELD OF THE INVENTION

This invention relates generally to directional drilling, and more specifically to directional drilling with air hammer drilling tools or non impact drill bits used in air drilling.

BACKGROUND OF THE INVENTION

Currently, underground directional drilling has been largely limited to drilling with roller cone or polycrystalline diamond compound (PDC) type bits with mud or air-mist rotary drilling motors utilizing rotor-stator or similar technologies. These technologies use liquid based drilling fluids. Large portions of the drilling industry use air hammer drilling tools also known as drill hammers for conventional straight-hole drilling that strictly use air as the drilling medium. However, rotor-stator technology is not suitable or too expensive for air hammer drilling tools. Consequently, the air hammer drilling industry has had limited access to the benefits of directional drilling.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an underground directional drilling mechanism that allows standard air hammer drilling tools to be utilized in the directional drilling process by the rotating a drill hammer during the impact process without rotating the drill string. These and other objects and advantages of the invention will become readily apparent as the following description is read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment of the present invention;
FIG. 2 shows three primary components of the embodiment shown in FIG. 1;
FIGS. 3A and 3B shows detail of the motor assembly of the embodiment shown in FIGS. 1 and 2;
FIG. 4 shows detail of the bent sub assembly of the embodiment shown in FIG. 1;
FIG. 5 shows detail of the bottom bearing assembly of the embodiment shown in FIG. 1;
FIG. 6 shows a drill path used by the present invention;
FIG. 7 shows the motor assembly cut along the lines A-A of FIG. 3; and
FIG. 8 shows a retaining ring cut along the lines B-B of FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before explaining the disclosed embodiment of the present invention in detail it is to be understood that the invention is not limited in its application to the details of the particular arrangement shown, since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation.
The present invention uses standard air hammer drilling tools and utilizes them in the directional drilling process. Existing hammer tools can be used without modification. In addition, the present invention generates enough torque to use conventional drill bits in some applications. The present invention achieves this by operating a drilling motor rotation device that uses compressed air from an above-ground compressor to rotate down-hole percussive or hammer drills in oil and gas well drilling, or other down-hole drilling applications.
As will be shown in more detail below, the present invention incorporates a commercially available vane-type pneumatic air motor, a planetary gear box including a single-piece stem pinion gear made from hardened steel, and multiple universal joints, among other features. The entire device is attached to the bottom of the drill-string (thus below-ground).
The present invention performs directional drilling by rotating a down-hole percussive hammer drill without rotating the cylinder housing or drill string. It also uses an air driven motor mounted within the device that receives power from above-ground air compressor. It also has sealed tapered roller bearings used for centering the drive shaft and shouldering thrust and radial loads on the device.
One advantage of the present invention is that it can utilize any of a variety of commonly available air hammers. It is also an advantage of the present invention to not rotate the entire drill string along with the hammer. The present invention has bypass tubes for delivering excess compressed air not used by the vane motor to the hammer drill for its operation. The present invention also has check valves that send exhausted air from the vane motor to the well-bore.
FIG. 1 shows the drill string 100 which comprises a motor assembly 300, a bent sub assembly 400, and a bottom assembly 500 attached to a hammer 600. The drill string 100 is controlled from above ground using a drill pipe 50.
The function of the hammer drill 600 is to pulverize rock with repeated linear blows. The drill string 100 simultaneously imparts rotation to the hammer 600 so that the buttons 604 on the hammer 600 do not repeatedly strike the rock surface in the same place. The hammer buttons 604 act as mini chisels. The cutting of the rock or other underground material takes place under the buttons 604. If the buttons 604 do not move (rotate), zero or minimal cutting takes place.
The drill string 100 rotates the entire hammer drill 600 in rotations per minute similar to rotations supplied by the drilling rig and drill string. This allows the buttons 604 to rotate across the entire face of the borehole and thus cut the entire face. Additionally, the drill string 100 supplies sufficient torque to overcome the drag on the hammer 600 from the sides of the borehole that hamper rotation.
Since the motor 300 supplies the rotation of the hammer 600, the exterior of the drill string 100 itself need not rotate. This allows for the bend in the middle of the bent sub assembly 400 so as to impart a direction to the drilling action. As shown in FIG. 1, the bit of the hammer 600, the outside edge of the bent sub 400, and the end of the motor assembly 300 form three points in space that are not in a straight line but instead form an arc. This arc is the amount of curvature created during the drilling process as the well bore goes from vertical at the beginning of the drilling process, to greater and greater angles from vertical as the drilling progresses around the arc until a horizontal angle is achieved.
For the present invention to achieve maximum effectiveness and convenience, the rotary power source must use the same power source as the linear power source for the air hammer 600. Having two separate power sources is not cost-effective, and is also more difficult to implement. In an exemplary embodiment, the motor assembly 300 uses compressed air, although the present invention should not be considered as limited exclusively thereto.
As shown in FIG. 6, the well-bores contemplated within the present invention are usually drilled within very narrow space constraints. The present invention is customized to get it in the shape and space which is as small a space possible. The present invention is suited for well-bores as small as 6¼ inches in diameter. Thus, the drill string 100 of the present invention is ideally less than six inches in diameter, although other implementations are possible. The smaller size is needed to have room in the bore hole for the drill string 100 that incorporates a bent sub assembly 400 to get down to the intended drill space and to provide room for cuttings and air to return past the drill string 100 and up the borehole. Thus, in an exemplary embodiment, the drill string 100 of the present invention measures 5½ inches outside diameter.
As shown in FIG. 2, the total outside diameter of the drill string 100 must allow for several threaded connectors on 324, 424, 504, and 524 to fasten all pieces 300, 400, 500, and 600 together. Additionally, the motor 304 must be small enough to fit inside the aperture within the drill string 100. As shown in FIG. 2, the bottom assembly 500, the bent sub assembly 400, and the motor assembly 300 are joined together with coarse threads. The threaded connectors on 324, 424, 504 and 524 are assembled with torques sufficient to keep the drill string 100 from disassembling during use, and are also designed to withstand very high tensional forces occasionally encountered during the drilling process, as well as provide a tight seal for routing the air necessary to drive the hammer 600.
As shown in FIG. 3A, the present invention uses part of the compressed air stream that is supplied by the above-ground drilling rig or auxiliary compressor to operate the hammer drill. Typically, hammer drills in the air drilling process require between 600 and 900 cubic feet of air per minute to operate and remove drill cuttings from the borehole. If more air is needed, then an auxiliary compressor can be added.
As shown in FIG. 3B, a regulator 338 will limit the air pressure of the compressed air before it gets to the vane motor 304. Air pressure is regulated so as to not overdrive the vane motor 304 yet provide the optimum pressure for the vane motor to function effectively. The vane motor 304 has devices that turn like the blades of a fan or turbine. The regulator and motor are located in a low pressure air chamber contained by a motor housing plate 390.
As shown in FIG. 3B, the motor assembly 300 has check valves 342 which are the ports where the air is exhausted out from the vane motor 304 to the well bore. The check valves 342 keep fluids and cuttings from entering the interior of the device when air is not being exhausted. This exhaust air is the same approximate 100 cubic feet per minute air that is used to run the vane motor 304 that supplies the power to the sun pinion 312 and planet gears 316, and in turn drive the keyed shaft 334. The exhausted air also aids in cuttings removal. The check valves 342 are one-way so as to prevent drilled materials from flowing back into the drill string 100.
The regulator 386 ensures that a specific, fixed amount of air at a constant pressure arrives at the motor 304. Meanwhile, the air filter 380 preserves the motor 304. The filter 380 removes all coarse material typically found in compressed air streams found on drilling rigs.
The motor 304 must be small enough to fit inside the tube of the motor assembly 300, and also allow space for tubing 311 to be placed alongside the motor 304. As shown in FIGS. 3A and 3B, this tubing 311 allows a supply of air from the above ground air compressor to be not directed at the motor 304 and instead be supplied to the hammer 600.
As shown in FIG. 3B, the motor assembly 300 also contains threaded plugs for lubrication. The plugs will allow the insides of the gearbox in the motor assembly 300 to be filled with lubricating oil or grease after the device is assembled. The threaded screws 308 attach the gearbox housing and motor mount plates to the exterior tube of the motor assembly 300.
The top gear hub and the gear hub base (FIG. 3A) exist to hold the planet gears 316 in place with the proper alignment, so that they have the optimum contact with the sun pinion 312. FIG. 3A shows a helical gear configuration in the gearbox. However, other embodiments such as a configuration with spur gears may also be utilized.
The gearbox housing 314 is comprised of the internal gear and two end plates. The gearbox housing remains fixed because it is attached to the wall of the outside shell of the housing 324 by housing screws 308. The planet gear assembly rotates inside the cavity of the gearbox housing. As shown in FIG. 3A, the motor 304 has a square shaft that is attached to the stem pinion sun gear 312 that has a square socket.
As shown in FIG. 4, within the bent sub assembly 400 there are 2 U-joints. These act as two different independent links, with another shaft 428 in between the two. The two universal joints thus work in tandem, so that the rotation of the drive shaft through the bent sub 400 has a smooth action. A square shaft 420 is attached to the bottom universal joint.
As shown in FIG. 5, the square shaft fits in a slip sleeve that transfers torque from the universal joints to the drive shaft 510. One half inch keyways and keys are used to impart torque from the gearbox keyed shaft to the top universal joint, between the universal joints, and between the bottom universal joint and the square shaft 420. Two ½ inch keyways and keys impart the torque from the keyed shaft 334 to the universal joints and shaft 428 in the bent sub 400.
As shown in FIG. 4, the bent sub assembly 400 can be built with a specific angle bend, measured in degrees. As shown in FIG. 4, the bent or sloped area 484 can be built with a variety of slopes or bends, hence the name “bent sub assembly”. Some exemplary measurements can be 0.75 degrees, 1 degree, 2 degrees, and potentially higher amounts. An operator of the present invention can adjust the amount of angle created during the drilling process by changing out the bent sub assembly 400 with an assembly that has a different bend.
As shown in FIG. 5, the shear pins 504 attach the bearing supported drive shaft 520 to the box 505 where the hammer 600 is attached. The pins 504 secure the box to bearing supported drive shaft 420 under normal and occasionally high tension loads sometimes experienced in certain in down-hole conditions. Keyways and keys are placed perpendicular to the pins 504 to impart torque from the drive shaft 520 to the box 505. The optional stabilizer 534 keeps the tool centered in the hole and keeps most of the side load off of the hammer 600.
The drive shaft 510 is centered within the bearing housing 524 by means of tapered roller bearings 512. Accordingly, FIG. 5 shows how the bottom assembly 500 keeps the drive shaft centered with the roller bearings 512. The drive shaft is attached to the box coupling 505 by means of shear pins 504. The box coupling 505 is the bottom connection of the device that contains tapered threads 524 which connect to the threaded pin of the air hammer 600. The box coupling 505 transfers thrust loads from the hammer 600 to the bottom taper roller bearing 512. These tapered roller bearings 512 can take both axial and radial loads. By locating them opposite each other, as shown in FIG. 5, the bearings ensure that the hollow drive shaft remains centered and does not wobble.
The bottom assembly 500 further serves to transfer air flow channeled through the bent sub assembly 400 to the hammer 600. The hammer 600 obtains all of its non-rotational longitudinal hammering force from high pressure air flow. This air flow is sent through the interior aperture of the drive shaft 510 to the hammer.
The drive shaft 510 and box coupling 5050 is secured within the bottom assembly 500 by means of retaining rings. Accordingly, a retainer piece assembly 800 fits as shown in FIG. 8 ensures that the drive shaft does not slide through the top taper roller bearing.
FIG. 6 shows one possible implementation of the present invention. A drill string 100 is located within a wellbore. The exteriors of the motor assembly 300, bent sub assembly 400, and bottom assembly 500 do not rotate. However, the box coupling 505 and hammer 600 rotates. The entire drill string 100 is operated by making changes to the drill pipe 50 at the drill rig at the ground level.
It is important to understand how various portions of the drill string 100 rotate, while others do not. The planet gears 316 and sun pinion 312 as well as keyed shaft 334 rotate, while the threaded housings 324, 424, and 524 remain fixed. Additionally, the drive shaft 510, tapered roller bearings 512, coupling 505, shear pins 504, and drive shaft 520 all rotate.
A cross section of the motor assembly 300 is shown in FIG. 7, cut along the lines A-A in FIG. 3A. In FIG. 7, the single-piece stem pinion sun gear 312 made from hardened steel or other material, is bordered by planet gears 316. However, as stated, other types of gearing mechanisms could also be used, such as an arrangement of spur gears. Consequently, the present invention should not be considered as limited to specific type of gearing mechanism, and that numerous alternative gearing mechanisms can be contemplated within the spirit and scope of the present invention.
A perspective view of the retainer assembly is shown in FIG. 8, which is formed by cutting the bottom assembly 500 along the lines B-B as shown in FIG. 5. The retainer piece 800 consists of a two-piece retainer ring 516 and sleeve 520. The drive shaft 510 is notched on the exterior to fit the inside diameter of the two piece retainer ring 516. The two piece retainer ring 516 is secured against the hollow drive shaft by the retainer sleeve 520, and squeezes up against the drive shaft so as to prevent lateral movement.
The present invention is configured to allow for the compressed air not utilized by the vane motor 304 to bypass that motor and instead flow through the device to the air hammer 600. To achieve this bypass, the drill string 100 of the present invention has bypass tubes 311 that direct compressed air from the chamber that houses the filter past the chamber that houses the regulator 324 and vane motor 304 to a chamber housing the sun gear 312 and pinion gear 316.
As shown in FIGS. 3A, the gear box housing 314 has flutes cut laterally along its length to allow for the bypass air to reach the bent sub assembly 400. The air then flows past the universal joints in the bent sub assembly 400 to the bottom assembly 500. The air is then exhausted through the hollow drive shaft 510 and box coupling 505 to the air hammer 600.
It is an advantage of the present invention that it allows for a drilling process that requires minimal torque. Thus the connections within the drill string 100 can be made up with tools typically found on drilling rigs. No high torque tools are needed.
It is anticipated that various changes may be made in the arrangement and operation of the system of the present invention without departing from the spirit and scope of the invention, as defined by the following claims.

Claims

1. A directional and rotating drill mechanism, comprising:

an air compressor, for providing pneumatic energy to said mechanism;

a motor assembly, for rotatably driving a hammer which in turn rotatably contacts a wellbore area to be drilled, wherein said motor assembly uses pneumatic energy provided by said air compressor;

a bent sub assembly, connected to motor assembly; for controllably providing change in direction of said drill; and

a bottom assembly, connected to said bent sub assembly, for linearly driving and controlling said hammer, wherein said bottom assembly uses pneumatic energy provided by said air compressor;

wherein said motor, bent sub, and bottom assemblies are connected together in a drill string.

2. The mechanism of claim 1, further comprising:

said hammer having buttons positioned on its surface;

said hammer reciprocates within a portion of said bottom assembly so as to contact said area with repeated linear blows, wherein said mechanism simultaneously imparts rotation to said hammer so that said buttons on the hammer do not repeatedly strike the same area of said wellbore.

3. The mechanism of claim 1, further comprising:

said drill string is controlled from above ground using a drill pipe.

4. The mechanism of claim 1, further comprising:

said drill string rotates the entire hammer drill in rotations per minute similar to rotations supplied by the drilling rig and drill pipe, the buttons to rotate across the entire face of said borehole.

5. The mechanism of claim 1, further comprising:

said drill string is supplied sufficient torque energy by said air compressor to overcome the drag on the hammer from the sides of the borehole that hamper rotation.

6. The mechanism of claim 1, further comprising:

a motor inside said motor assembly is sufficiently small to fit inside the tube of the drill string.

7. The mechanism of claim 1, further comprising:

said motor, bent sub, and bottom assemblies are joined using threaded connectors.

8. The mechanism of claim 1, further comprising:

said joining occurs using sufficient torque so as to keep the drill string from disassembling during use.

9. The mechanism of claim 1, further comprising:

said drill string can withstand tensional forces encountered during the drilling process.

10. The mechanism of claim 7, further comprising:

said connectors provide a tight seal for routing the air necessary to drive the hammer.

11. The mechanism of claim 1, further comprising:

an auxiliary compressor to assists said air compressor.

12. The mechanism of claim 1, wherein said bottom assembly further comprises:

a regulator to limit the air pressure of the compressed air before it gets to the vane motor.

13. The mechanism of claim 6, further comprising:

an air regulator, connected between said air compressor and said motor, so that the air pressure from said compressor is regulated so as to not overdrive said motor, yet still provides optimum pressure for said motor to function.

14. The mechanism of claim 6, further comprising:

said motor has fins that turn like the blades of a fan or turbine.

15. The mechanism of claim 1, further comprising:

motor assembly has check valves which are the ports where the air is exhausted out from said vane motor to the well bore.

16. The mechanism of claim 15, further comprising:

said check valves keep fluids and cuttings from entering the interior of said drill string when air is not being exhausted.

17. The mechanism of claim 15, further comprising:

said check valves are one-way so as to prevent drilled materials from flowing back into said drill string.

18. The mechanism of claim 13, further comprising:

said regulator ensures that a specific, fixed amount of pressure arrives at the motor.

19. The mechanism of claim 13, further comprising:

an air filter, connected between said compressor and said regulator, for preserving said motor.

20. The mechanism of claim 19, further comprising:

said filter removes all coarse material typically found in compressed air streams found on drilling rigs.

21. The mechanism of claim 6, further comprising:

motor must be small enough to fit inside the tube of the motor assembly, and also allow space for air tubing to be placed alongside the motor.

22. The mechanism of claim 21, further comprising:

said tubing allows a supply of air from said air compressor to be not directed at the motor and instead be supplied to said hammer.

23. The mechanism of claim 1, further comprising:

said motor assembly contains threaded plugs for lubrication.

24. The mechanism of claim 1, further comprising:

a gear system for transforming pneumatic energy into rotational; located within said motor assembly.

25. The mechanism of claim 24, wherein said gear system further comprises:

a planetary gear system having a sun pinion gear at its center, surrounded by planet gears; and

a top gear hub and a gear hub base hold the planet gears in place with the proper alignment, so that they have optimum contact with the sun pinion gear.

26. The mechanism of claim 1, wherein said bent sub assembly further comprises:

two universal joints which act as two different independent links with another shaft in between the two so that they turn smoothly.

27. The mechanism of claim 26, further comprising:

said bent sub assembly can be built with a specific angle bend, measured in degrees.

28. The mechanism of claim 27, further comprising:

said bent or sloped area can be built with a variety of slopes or bends.

29. The mechanism of claim 1, further comprising:

a bearing supported drive shaft to a box coupling for which said hammer can be attached;

wherein said drive shaft is attached to said threaded housing using shaft pins.

30. The mechanism of claim 29, further comprising:

a plurality of pins secure the box to bearing supported drive shaft under normal and occasionally high tension loads.

31. The mechanism of claim 30, further comprising:

a plurality of keyways and keys are placed perpendicular to said pins to impart torque from the drive shaft to the box.

32. The mechanism of claim 1, further comprising:

an optional stabilizer, located within said bottom assembly, which keeps said drill string centered in the wellbore and keeps side load off said hammer.

33. The mechanism of claim 29, further comprising:

said drive shaft is centered within the bearing housing by means of tapered roller bearings.

34. The mechanism of claim 29, further comprising:

said box coupling transfers thrust loads from the hammer to a plurality of tapered roller bearings, which can withstand take both axial and radial loads.

35. The mechanism of claim 29, further comprising:

said drive shaft and box coupling is secured within the bottom assembly by means of retaining rings.

36. The mechanism of claim 22, further comprising:

motor assembly has flutes cut laterally along its length to allow for said tubing containing bypass air to reach the bent sub assembly.

37. A method of performing directional drilling, comprising:

providing pneumatic power to a drill string using a single power source;

applying a hammer attached to said drill string within a well shaft in a linear path using said pneumatic power; and

simultaneously rotating said hammer using said pneumatic power.